Answer:
C
Explanation:
because an ice is a solid and when it melts it becomes a liquid
Answer:
C
Explanation:
1) Which example shows a change in a state
of matter?
A. Liquid pouring
2
B. Wood Burning
1
C. Ice Melting
C when ice melts it goes from a solid to a liquid state
Methane (CH4) is used in laboratory burner. When 1 mole of methane burns at constant pressure, it produces 804 kJ of heat and does 3 kJ of work.Methane (CH4) is used in laboratory burner. When 1 mole of methane burns at constant pressure, it produces 804 kJ of heat and does 3 kJ of work.
The enthalpy ΔH of combustion is - 804 kJ. The change in internal energy ΔE of the reaction process is -801 kJ
The objective of this question is to determine the value of ΔH and ΔE of combustion is for 1 mole of methane.
If we look closely at the question, we will realize that at constant pressure, methane burns and produces heat of 804 kJ into the surroundings.
Since heat is released;
ΔH = -804 kJ
It also does a work of 3kJ, since work is done on the system
W = - 3kJ
According to the first law of thermodynamics;
ΔE = ΔH - W
ΔE = (-804 - (-3 )) kJ
ΔE = -801 kJ
Therefore, we can conclude that the in 1 mole of methane, the enthalpy ΔH of combustion is - 804 kJ. The change in internal energy ΔE of the reaction process is -801 kJ
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Calculate the pH when the following quantities of 0.100 M NaOH solution have been added to 50.0 mL of 0.100 M HCl solution
Answer:
see explanation
Explanation:
Given 0.100M NaOH + 50ml 0.100M HCl
If 50ml of 0.100M NaOH is added to 50ml 0.100M HCl => pH = 7
if less than 50ml of 0.100M NaOH => pH < 7
if more than 50ml of 0.100M NaOH => pH > 7.
Example:
50ml(0.100M NaOH) + 50ml(0.100MHCl) =>
0.500mole NaCl + 0.500mole H₂O
In this mix, both NaOH and HCl are converted to NaCl and H₂O and NaOH or HCl are no longer present giving a neutral solution. Since neither Na⁺ nor Cl⁻ undergo hydrolysis, the pH is dependent upon H₂O ⇄ H⁺ + OH⁻ and [H⁺] = [OH⁻] = 10⁻⁷M => pH = -log[H⁺] = -log(10⁻⁷) = -(-7) = 7
If less than 50ml of 0.100M NaOH is added, the mix will have an excess of HCl and the pH will be acidic; i.e., less than 7.
If more than 50ml of 0.100M NaOH is added, the mix will have an excess of NaOH and the pH will be alkaline (basic); i.e., greater than 7.
Write and balance the equation for the complete combustion of heptane, C7H16. Phase symbols and energy changes are optional.
The balanced equation for the complete combustion of heptane, [tex]C_{7}H_{16}[/tex] is given as,
[tex]C_{7}H16(g) + 11O_{2} (g)[/tex] → [tex]7CO_{2}(g) + 8H_{2}O(g)[/tex] + heat/light
What is combustion reaction?It is exothermic redox chemical reaction.The reaction between fuel and oxidant to produce oxidized product is called combustion reaction.The oxidant are usually atmospheric oxygen.The oxidized product is carbon dioxide gas and water.What is balanced chemical equation?The chemical equation in which number of atom each elements is equal in reactant and product of the reaction is called balanced chemical equation.
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*1. The internal energy with a system associated with the motion of particles and that can be added to a substance is called_____.
A. Thermal energy
B. Electrostatic forces
C. Temperature
D. Kinetic energy
•
•
•
*2. Which statement describes the effect of adding more energy to a system, assuming a phase change does not occur?
A. The particles within the system will have greater motion, and the temperature will decrease.
B. The particles within the system will have greater motion, and the temperature will increase.
C. The particles within the system will have less motion, and the temperature will increase.
D. The particles within the system will have less motion, and the temperature will decrease.
•
•
•
*3. Which statement correctly describes how attractions that hold particles break?
A. Attractions due to electrostatic forces. When particles have low enough energy, these forces can no longer keep particles together.
B. Attractions due to gravitational forces. When particles have low enough energy, these forces can no longer keep particles together.
C. Attractions due to gravitational forces. When particles move fast enough, these forces can no longer keep particles together.
D. Attractions due to electrostatic forces. When particles move fast enough, these forces can no longer keep particles together.
•
•
•
*4. Which statement explains why a rubber band analogy is not a perfect comparison for bonds in a substance when considering phase changes?
A. For a phase change from liquid to gas, the bonds break completely and particles can move independently of each other.
B. For a phase change from liquid to gas, the bonds do not break completely and the particles can still slide past each other.
C. For a phase change from solid to liquid, the bonds break completely and particles can move independently of each other.
D. For a phase change from solid to liquid, the bonds do not break completely in the particles can still slide past each other.
•
•
•
*5. The boiling point of benzene is 80°C. Which pair of samples will have the same average kinetic energy as benzene molecules?
A. Two samples of liquid benzene, one at 70°C in the other at 80°C.
B. A sample of liquid benzene at 70°C and a sample of gaseous benzene at 90°C.
C. Two samples of gaseous benzene, one at 80°C in the other at 90°C.
D. A sample of liquid benzene at 80°C and a sample of gaseous benzene at 80°C.
Answer:
1. thermal energy
2. the particles within the system will have greater motion, and the temp will increase.
3. attractions occur due to electrostatic forces. when particles move fast enough, these forces can no longer keep particles together.
4. for a phase change from a solid to liquid, the bonds do not break completely and particles call still slide past each other.
5. a sample of liquid benzene at 80°C and a sample of gaseous benzene at 80°C
Explanation:
hope this helps
Temperature is a measure of the average kinetic energy of molecules.
The particles of a substance are in constant random motion. As more thermal energy is added to the particles, the motion of the particles increases. If more energy is added to a system during phase change, the particles within the system will have greater motion, and the temperature will increase.
Attractions between particles is greater when the kinetic energy of molecules decreases. Therefore, a statement that correctly describes how attractions that hold particles break is; "attractions due to electrostatic forces. When particles move fast enough, these forces can no longer keep particles together."
The rubber analogy is commonly used to describe covalent bonds where stretching of bonds occur. This analogy is not apt in describing phase changes because for a phase change from a solid to liquid, the bonds do not break completely and particles call still slide past each other.
The average kinetic energy of molecules depend on temperature hence a sample of liquid benzene at 80°C and a sample of gaseous benzene at 80°C will have the same average kinetic energy.
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A student experimentally determines the gas law constant, R, by reacting a small piece of magnesium with excess hydrochloric acid and then collecting the hydrogen gas over water in a eudiometer. Based on experimentally collected data, the student calculates R to equal 0.0832
Due to errors in volume and moles measurement by the student, the true value of the molar gas constant is less than the obtained value.
The Percent error is 1.39%
What is percent error?Percent error is defined as the ratio of error and true value of a measurement expressed as a percentage.
Percent error = (error/true value) × 100%Error = |true value - measured value|
The error in the students measurement = |0.08206 - 0.0832|
Error = 0.00114
Percent error = (0.00114/0.08206) × 100%
Percent error = 1.39%
The formula to determine the molar gas constant R is given below:
[tex]R = \frac{PV}{nT}[/tex]
Since the student value is higher than the true value, the possible sources of error include:
The student student does not equilibrate the water levels within the eudiometer and the beaker at the end of the reaction resulting in increased volumeThe student does not clean the zinc with sand paper, thus the number of moles of hydrogen gas produced is less than the actual value.Therefore, the true value of the molar gas constant is less than the obtained value.
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An atom has the following electron configuration.
1s22s22p63s23p64s2
How many valence electrons does this atom have?
Answer:
2
Explanation:
4s2 has 2 valence electrons
Valence shell is the shell which is the outermost shell, that is filled in the last, before valence shell is penultimate shell. Therefore 2 valence electron are there in the valence shell.
What is element?Element generally consist of atoms or we can say atoms combine to form element. Atoms of an element is always same, means all the properties of all atoms of one type of element is same.
From our question the electronic configuration of element is given as
1s²2s²2p⁶3s²3p⁶4s²
Valence electron is the one which is present in the outermost shell or orbit. So, form above electronic configuration we can say that 4 is the outermost shell and in this shell 2 electron is present. Therefore 2 electron are there in the valence shell as valence electron.
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How many molecules are present in 4.61x10-2 mol of O2
Answer:
6.02 × 1023
The molar mass from the periodic table is 32.00 g O2 = 1 mol O2, and by definition, 1 mol O2 = 6.02 × 1023 molecules O2.
Which of the following frequencies of light has the lowest energy?
Answer:
Radio waves have photons with the lowest energies. Microwaves have a little more energy than radio waves. Infrared has still more, followed by visible, ultraviolet, X-rays and gamma rays.what is the best way to learn and understand high school chemstry?
Answer:
Firstly, try to Go through your chapter and pay attention to main keywords.
secondly try to watch 'Uube' videos related to specific topic instead of chapter and pay attention to it closely and watch it with a keen interest.
Discuss topics that you find harder with your friends or peer group members, Because you learn faster when you study with the people of your age.
Answer:
i think the best way to learn chemistry is study over things that involve it
Explanation:
Help please :) with this
Answer:
The answer is 3
Explanation:
Hope this helps and have a wonderful day.
Fusion is a type of _____.
chemical reaction
nuclear reaction
physical reaction
Answer:nuclear reaction
Explanation: Nuclear fusion is a type of nuclear reaction where two light nuclei collide together to form a single, heavier nucleus. Fusion results in a release of energy because the mass of the new nucleus is less than the sum of the original masses.
Fusion is the process that powers the sun and the stars. It is the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium. In the process some of the mass of the hydrogen is converted into energy.
name 2 elements that are liquid at room temperature and describe their colour
Answer:
Bromine
Mercury
Bromine (symbol Br and atomic number 35) is a reddish-brown liquid, with a melting point of 265.9 K. Mercury (symbol Hg and atomic number 80) is a toxic shiny silvery metal, with a melting point of 234.32 K.
If a barometer were built using water (d=1.0 g/cm3) instead of mercury (d=13.6 g/cm3), would the column of water be higher than, lower than, or the same as the column of mercury at 1.00 atm? If the level is different, by what factor? Explain.
Explanation:
A more dense liquid stays lower while a less dense liquid stays higher. since water is 13.6 times less dense than mercury, the column for a barometer using water would have to be 13.6 times taller.
Help with this please
Answer:
12
Explanation:
There are 4 sulfur atoms in SO4
4×3=12
This means that it turns into 3×(SO4)
=3SO4
What is the molality of sodium chloride in solution that is 13.0% by mass sodium chloride and that
the solution has a density of 1.10 g/mL?
Answer:
2.4 M
Explanation:
1. Suppose you have 100 mL solution:
Use density to find grams of solution:
100 mL solution x (1.10 g / 1 mL) = 110 g solution
2. FInd the amount of sodium chloride pure:
110 g solution x(13 g NaCl / 100 g solution) = 14.3 g NaCl
3. Change grams to mol:
14.3 g NaCl x ( 1 mol NaCl/ 58.44 g NaCl) = 0.24 mol NaCl
4. Molarity:
M = mol NaCl / L solution
M = 0.24 mol NaCl / 0.1 L = 2.4 M
For the diprotic weak acid H2A, a1=3.2×10−6 and a2=6.1×10−9 .
What is the pH of a 0.0750 M solution of H2A ?
What are the equilibrium concentrations of H2A and A2− in this solution?
In the first dissociation of H2A:
molarity H2A(aq)↔ (HA)^-(aq) + H^+(aq)
initial 0.05 m 0 m 0 m
change -x +x +x
equilibrium 0.05-x x x
we can neglect X in [H2A] as it so small compared to the 0.05
so by substitution in Ka equation:
Ka1 = [HA][H] / [H2A]
2.2x10^-6 = X^2/0.05
X = √(2.2x10^-6)*(0.05)= 1.1x10^-7
X= 3.32x10^-4 m
∴ [H2A] = 0.05 - 3.32x10^-4 = 0.0497 m
[HA] = 3.32x10^-4 m
[H] = 3.32x10^-4 m
the second dissociation of H2A: when ka2 = 8.2x10^-9
HA-(aq) ↔ A^2- (aq) + H+(aq)
at equilibrium 3.32x10^-4 y 3.32x10^-4
Ka2 = [H+][A^2-] / [HA]
8.2x10^-9 = Y(3.32x10^-4)/(3.32x10^-4)
∴y = 8.2x10^-9 m
∴[A] = 8.2x10^-9 m
PH= -㏒[H+]
= -㏒(3.32x10^-4)= 3.479
[A]=8.2x10^-9 m
[H2A] = 0.0497 ≈ 0.05 m
How does the structure of compounds determines the properties of the compounds?
All of these properties are due to the chemical structure of the compound. The chemical structure includes the bonding angle, the type of bonds, the size of the molecule, and the interactions between molecules. Slight changes in the chemical structure can drastically affect the properties of the compound.
Hitting a ball with a baseball bat is an example of a force
True or False
What does percent composition tell you about a molecule?
O A. It tells you how the elements are arranged in the molecule.
B. It tells you the ratio of elements in the molecular formula.
C. It gives you the total number of atoms in the molecule.
D. It tells you how much of a molecule is made up of each element.
SUBMIT
Answer:
B
Explanation:
percentage composition helps to determine the percentage of each element in a compound
a
A molecule that experiences London dispersion forces is
likely to have a • boiling point than a molecule
experiencing a dipole-dipole interaction.
pls
Answer:
it should be the second one since London dispersion causes interaction between molecules.
hope I helped.
Generally non ionic species with no polarity forms the London -dispersion bonds. London dispersion is weaker than the dipole-dipole interaction and hence it have less boiling point.
What is boiling point?Boiling point of a substance is the temperature at which the substance changes from liquid state to gaseous state or vapor where, the two states are in equilibrium.
Boiling of a substance depends on the molecular weight, bond type,temperature, pressure as well as purity of the substance.
London dispersion force is formed between two non-polar atoms. These atoms when come closer they attains a temporary polar nature and gets bonded.
Dipole-dipole bond is formed between two atoms of permanent dipole moment and they are polar compounds. Thus dipole-dipole interaction is stronger than London dispersion interaction. A strong bond needs more energy to boil.
Hence, molecules with Dipole-Dipole bond is having higher boiling point.
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How large
would be needed to hold
a Container
of water
Answer:
Since water has a density of 1 gram per cubic centimeter, then the container would need to be 800 cubic centimeters. if this container were a perfect cube, then the length of the side of the container would be equal to the cube-root of 800, which is approximately 9.28 cm to a side, or 3.65 inches to aside.
Air is a mixture of (mostly) oxygen (molecular mass 16) and nitrogen (molecular mass 14) gases. At room temperature, which molecules in this room have more kinetic energy (on average)
The molecules of the two gases will have the same kinetic energy at room temperature.
The average kinetic energy of gaseous molecules can be calculated using the formula:
Kinetic Energy = 3/2RT, where R = constant and T = temperature in Kelvin
This means that the kinetic energy of a gaseous molecule is dependent on the temperature of the molecule only.
In other words, the molecular mass of molecules of gases has no bearing on the kinetic energy of each molecule.
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Someone plz help me asap
Answer: it would be the stem and the roots of the plant
Explanation:
QUESTION 27
20 points
Compare and contrast how the selection of police officers in 1840s New York differed from police officer selection under the European
model.
Explanation:
During the 1800s in England, relations police, which became composed of male volunteers, became organised to observe over the protection and protection in their relatives. As Britain's populace step by step expanded, so did the quantity of crimes tha…
During the 1800s in England, relations police, which became composed of male volunteers, became organised to observe the protection and protection of their relatives.
What is protection?Protection is any measure taken to guard a thing against damage.
During the 1800s in England, relations police, which became composed of male volunteers, became organised to observe the protection and protection in their relatives.
As Britain's populace step by step expanded, so did the number of crimes that had been committed. This intended that regulation and order additionally needed to improve.
The New York City Police Department (NYPD) originates withinside the Government of New York City and tries to manipulate growing crime in early to mid-nineteenth century New York City.
This expanded crime became because of an expanding populace, brought about usually through negative Irish immigrants starting withinside the 1820s.
Whereas, as societies have become greater heterogeneous and complex, the function of the police is turning greater demanding. To fulfil this function, law enforcement officials want numerous broadly acknowledged competencies and private qualities, however much less is thought approximately how they're valued through police recruits.
Thus, we've tested the perspectives of police recruits in six European nations on 3 skills or traits of regarded significance for police work: knowledge, leadership, and the cap potential to shape precise family members with residents.
We have additionally explored versions in perspectives of recruits in distinct businesses and modifications of their perspectives for the duration of their schooling. For those purposes, we used survey facts accumulated withinside the RECPOL project.
Since the facts had been accumulated from distinct populations and at distinct times, the evaluation is primarily based totally on dimension invariance methodology, and one of the objectives became to spotlight the significance of rigorous appraisal of the pleasant and comparison of comparable survey facts the use of such methods.
The consequences display each variation and similarities in perspectives of recruits withinside the surveyed nations and modifications for the duration of schooling.
Police lifestyle seems to be an extensive factor, as greater objects withinside the carried out device can be validly utilized in comparisons of recruits in businesses with comparable policy traditions.
The consequences additionally confirmed exciting contrasts, e.g. new recruits in Sweden rated precise family members with residents greater surprisingly than recruits in businesses with a greater army history, however, this sample was modified for the duration of schooling, probably because of the effects of the recruitment process, schooling and lifestyle in the businesses.
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please help me! giving brainliest!!
Answer:
It is a covalent bond because both carbon and oxygen are nonmetals. The formula will be CO² because the electrons between the atoms are being shared equally.
Answer:
Option C
Explanation:
CO₂ is a covalent bond because we know that both elements are nonmetals. The carbon atoms shares 2 electrons with each oxygen atom and each oxygen atom shares two electrons with the carbon atom. CO₂ forms a nonpolar covalent bond, meaning that the electrons are shared equally.
Two students are identifying a sample of tap water.
Student A says that tap water is a mixture, while
Student B says that it is a compound. Which student
is correct? Justify your answer.
Tap water is a mixture not compound due to presence of many substance.
Tap water is an example of mixture not compound because in tap water, water is not available in pure form, it has many substances mix with water and those substances make no bond with water.
It has dissolved compounds like calcium carbonate, magnesium and fluoride. Different elements or compounds are physically combined rather than chemically linked together so we can conclude that student A is correct that tap water is a mixture.
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Which one of these is not an important structural feature found by the number of
electron rich regions
Hybridization
Bond Angles
Electronegativity
Electron Geometry
Answer:
Electronnegativity
Explanation:
There are three important structural features: Hybridization, Bond angels, and Electron Geometry.
The not so important structural feature found by the number of electron rich regions is electronegativity. Hence option c is correct.
What are structural feature?Structural feature is defined as the modeled as a directed acyclic graph (DAG), with the variable names as pathways and the variable values as nodes. The study of the construction of biological molecules is known as structural biology. Scientists study molecules in three dimensions using a range of imaging techniques to examine how they are put together, how they work, and how they interact.
Electronegativity is defined as the propensity for atoms involved in covalent bonds to draw the bonding electrons. The negatively charged electrons are drawn to the positively charged protons in the nucleus. The electronegativity or attraction will rise with the number of protons in the nucleus. Therefore, in a row of the periodic table, electronegativity rises from left to right.
Thus, the not so important structural feature found by the number of electron rich regions is electronegativity. Hence option c is correct.
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I am not feeling well
I hope you feel better soon! :)
Calculate the mass of butane needed to produce 57.3 g of carbon dioxide.
Answer:
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[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
[tex]tex]\purple{\rule{45pt}{7pt}}\blue{\rule{45pt}{999999pt}}[/tex]
A carrot originally has a mass of 0.39g and after being left in a salt solution overnight it gained 0.3g. Calculate the percentage mass increase of the carrot.
Answer:
77%
Explanation:
The formula for finding percent change is change/original.
So, you have to do 0.3/0.39
You have to divide this to get 0.769 which can be rounded 0.77
0.77 as a percentage is 77%
So, the percentage mass increase of the carrot is 77%